A Global Sand Budget—A Discussion of Sand Generation, Use and Destruction. Are We Running Out of Sand?

Abstract

Recent articles on soil erosion sound the alarm regarding the large amount soil that is being lost due to modern agricultural practices, and there is a general concern that we may be destroying our sand and soil resources at rates that greatly exceed generation and preservation rates. There is also a general concern in the sand and aggregate industry as to whether sand is a renewable natural resource. The paper is unique and important to soil science as well as geology because it pulls together data from diverse sources in an attempt to summarize global rates of sand and soil generation from parent material, rates of sand consumption by humans, and rates of sand loss to humans through erosion and transportation to the oceans. While there is considerable literature on rates of soil erosion, there is remarkably little literature on rates of sand or soil generation from parent materials. Where rate numbers were found they were commonly local, and not global. They were commonly highly variable, and many conversions were required to put them in common, global units. Through a number of assumptions and calculations, the following conclusions have been made for global sand rates. (1) Sand is being generated from primordial granites at rates estimated at 1.6 billion tons/year. (2) Sand is being generated from soils at rates that range between 0.06 and 450 billion tons/year globally with an average of the most reasonable sources at 5.0 billion tons/year. (3) Sand today, through erosion and natural causes, is lost to the oceans at rates estimated at 4.8 billion tons/year. (4) Modern erosion rates are considered to be an order of magnitude greater than pre-human erosion rates, or about 0.5 billion tons/year. (5) Construction grade sand is currently mined at approximately 4.5 billion tons/year and industrial grade sand is consumed at about 0.2 billion tons/year for a total human usage estimated at 4.7 billion tons/year. Thus, total sand consumption by humans is slightly less than global generation rates, and an argument can be made that sand is a renewable natural resource. However, if modern rates of erosion and loss to the oceans are considered, then we are losing considerable ground with regard to total sand and soil availability.